+my ($default_cert, $default_key);
+my %KNOWN_TLS = ( 443 => 'https', 563 => 'nntps' );
+my %KNOWN_STARTTLS = ( 119 => 'nntp' );
+
+sub accept_tls_opt ($) {
+ my ($opt_str) = @_;
+ # opt_str: opt1=val1,opt2=val2 (opt may repeat for multi-value)
+ require PublicInbox::TLS;
+ my $o = {};
+ # allow ',' as delimiter since '&' is shell-unfriendly
+ foreach (split(/[,&]/, $opt_str)) {
+ my ($k, $v) = split(/=/, $_, 2);
+ push @{$o->{$k} ||= []}, $v;
+ }
+
+ # key may be a part of cert. At least
+ # p5-io-socket-ssl/example/ssl_server.pl has this fallback:
+ $o->{cert} //= [ $default_cert ];
+ $o->{key} //= defined($default_key) ? [ $default_key ] : $o->{cert};
+ my %ctx_opt = (SSL_server => 1);
+ # parse out hostname:/path/to/ mappings:
+ foreach my $k (qw(cert key)) {
+ my $x = $ctx_opt{'SSL_'.$k.'_file'} = {};
+ foreach my $path (@{$o->{$k}}) {
+ my $host = '';
+ $path =~ s/\A([^:]+):// and $host = $1;
+ $x->{$host} = $path;
+ }
+ }
+ my $ctx = IO::Socket::SSL::SSL_Context->new(%ctx_opt) or
+ die 'SSL_Context->new: '.PublicInbox::TLS::err();
+
+ # save ~34K per idle connection (cf. SSL_CTX_set_mode(3ssl))
+ # RSS goes from 346MB to 171MB with 10K idle NNTPS clients on amd64
+ # cf. https://rt.cpan.org/Ticket/Display.html?id=129463
+ my $mode = eval { Net::SSLeay::MODE_RELEASE_BUFFERS() };
+ if ($mode && $ctx->{context}) {
+ eval { Net::SSLeay::CTX_set_mode($ctx->{context}, $mode) };
+ warn "W: $@ (setting SSL_MODE_RELEASE_BUFFERS)\n" if $@;
+ }
+
+ { SSL_server => 1, SSL_startHandshake => 0, SSL_reuse_ctx => $ctx };
+}
+
+sub sig_setmask { sigprocmask(SIG_SETMASK, @_) or die "sigprocmask: $!" }